The present invention relates to a disc recording apparatus for recording data onto e.g. a magneto-optical disc while detecting defective sectors. The present invention also relates to a method for the apparatus to replace a sector on the recording disc. The present invention further relates to the recording disc.
Due to increased capacity, magneto-optical discs in recent years have an increasingly narrow track pitch. This has increased probability of error occurrence when writing data on the magneto-optical disc. At the time of data writing error, a retry is made as many times as predetermined. If the data writing is not successful within the predetermined number of retries, a decision is made finally that the writing has failed. A recent tendency is that the number of retries (retry count) is also increasing. This means that a long time is spent in vain for retries, resulting in prolonged access time. Consequently, there is a need for a technique to reduce the access time.
As shown in FIG. 11, a conventional recorder/player A10 formats a magneto-optical disc B10 in response to a command from a host personal computer C10. During the formatting, a CPU 110 of the recorder/player A10 writes initializing data onto each sector that provides a unit recording-area on the magneto-optical disc B10.
During this formatting, when there is a failure in writing the initializing data in one of the sectors, the CPU 110 makes a retry until the predetermined number of retries is reached. If the writing is not successful within the predetermined number of retries, the CPU 110 stores the address of the failed sector in a RAM 120 in the form of PDL (Primary Defect List). At the end of the formatting, the PDL is recorded as part of medium management information B11 on the magneto-optical disc B10.
On the other hand, the sectors onto which the initializing data was successfully recorded within the predetermined number of retries do not have their addresses listed in the PDL, and are allowed for use as flawless sectors. Such a formatting procedure is executed to all the sectors which are to be formatted.
Now, description will be given more about the PDL. FIG. 12 shows a zone without any defective sectors. Now, compare FIG. 12 to FIG. 13: When a defective sector is found in a data zone while formatting a magneto-optical disc B10, the defective sector is skipped, and the initializing data is written onto the next sector. In this way, the data zone including the defective sector is extended into a spare zone in order to provide a predetermined number of flawless sectors by using a spare sector(s) available in the spare zone. The address of the defective sector is stored in the RAM 120. Such a defect, i.e. a defect in which address can be assigned while skipping a defective sector, is called primary defect. A set of addresses of the defective sectors that fall into the category of the primary defect is called PDL.
Now the formatting is over. When actual data is written onto this magneto-optical disc B10, the CPU 110 of the recorder/player A10 writes the actual data onto a sector specified by an address in response to a xe2x80x9cwritexe2x80x9d command from the personal computer C10.
When the writing of the actual data is not successful, the CPU 110 makes a retry until a predetermined number of retries is reached. If the writing of the actual data is still not successful within the predetermined number of retries, the CPU 110 recognizes this sector that does not accept the actual data, as a defective sector, and then performs a replacement procedure in which the actual data is written onto another sector.
Specifically, during the replacement procedure, the CPU 110 searches a spare zone which immediately follows the data zone including the defective sector, selects an unused spare sector closest to the defective sector, as a replacement sector, and writes the actual data onto the replacement sector.
If the replacement sector does not allow writing, the CPU 110 makes a retry, seeking for another replacement sector. If the writing of the actual data is not successful within a predetermined number of retries, then another cycle of the replacement procedure is performed.
Such a replacement procedure performed within the spare zone is called re-replacement procedure, in which the cycle of seeking a replacement spare is repeated until the actual data is successfully written so long as a predetermined number of retries is not yet been reached.
When the actual data has been successfully written within the predetermined number of retries, the CPU 110 records addresses of the defective sectors that did not allow writing of the actual data, in the form of SDL (Secondary Defect List) in the medium management information B11 of the magneto-optical disc B10, and then reports to the personal computer C10 the successful completion. When the actual data has not been successfully written within the predetermined number of retries, the CPU 110 reports a disc error to the personal computer C10.
Now, description will be given more about the SDL. FIG. 12 shows a zone without any defective sectors. Now, compare FIG. 12 to FIG. 14: When a defective sector is found while writing actual data, the actual data is written in a sector in the spare zone, in place of the defective sector. Then, the address of the defective sector which was replaced and the address of the spare sector which replaced are recorded onto the medium management information B11. Such a defect, i.e. a defect in which a replacing spare sector can be specified by address conversion, is called secondary defect. A set of addresses of the defective sectors that fall into the category of the secondary defect is called SDL.
With the above, the CPU 110 performs the replacement procedure when a defective sector is found while writing actual data based on an address specified by the host personal computer C10. However, there is no guarantee that the writing will be successfully completed in the replacing sector. Sometimes, the replacing sector has a higher error probability than the replaced sector which was found defective. Thus, there have been cases in which the replacement procedure was repeated in vain to such a replacing sector, before the re-replacement procedure was finally inaugurated.
As understood, execution of the re-replacement procedure means that the replacement procedure is repeated twice or even more times in order to write actual data onto one sector, that a huge number of retries must be made for the writing of actual data, and as a result, that a long time is needed for the writing of actual data including the time spent for the replacement procedures. This creates a delay in response to the xe2x80x9cwritexe2x80x9d command from the personal computer C10, leading to a xe2x80x9ctimeoutxe2x80x9d error in the personal computer C10.
It is therefore an object of the present invention to provide a disc recording apparatus, a method for replacing sector on a recording disc and the recording disc, capable of reducing the access time without spending as much time when data writing is not successful.
A first aspect of the present invention provides a disc recording apparatus for writing data onto a sector providing a recording area on a recording disc. Upon failure in the writing, the apparatus performs a retry until a predetermined number of retries is reached, treats the sector as a defective sector upon failure in the last retry of the predetermined number of retries, and writes the data onto another sector. The apparatus comprises: a recording section recording onto the recording disc a retry count as retry count information for each of recovered sectors recovered from the failure through success in the writing of data during the retry; and a sector replacing section selecting a replacement sector for the defective sector detected upon the failure in the writing onto the recording disc containing the retry count information recorded by the recording section. The replacement sector has a retry count stored as the retry count information smaller than that of the defective sector.
A second aspect of the present invention provides a disc recording apparatus for writing data onto a sector providing a recording area on a recording disc. Upon failure in the writing, the apparatus performs a retry until a predetermined number of retries is reached, treats the sector as a defective sector upon failure in the last retry of the predetermined number of retries, and writes the data to another sector. The apparatus comprises: a storing section storing a retry count as retry count information for each of recovered sectors recovered from the failure through success in the writing of data during the retry; and a sector replacing section selecting a replacement sector for the defective sector detected upon the failure in the writing onto the recording disc for which the retry count information is stored by the storing section. The replacement sector has a retry count stored as the retry count information smaller than that of the defective sector.
According to a preferred embodiment, the sector replacing section registers a sector as a defective sector onto the recording disc if the sector is found to have a retry count stored as the retry count information larger than that of the defective sector during the process of selecting the replacement sector.
A third aspect of the present invention provides a method for replacing a sector for writing data onto a sector providing a recording area on a recording disc. Upon failure in the writing, the method performs a retry until a predetermined number of retries is reached, treats the sector as a defective sector upon failure in the last retry of the predetermined number of retries, and writes the data onto another sector. The method comprises: a step of recording onto the recording disc a retry count as retry count information for each of recovered sectors recovered from the failure through success in the writing of data during the retry; and a step of sector replacing control for selecting a replacement sector for the defective sector detected upon the failure in the writing onto the recording disc containing the retry count information recorded by the recording section. The replacement sector has a retry count stored as the retry count information smaller than that of the defective sector.
A fourth aspect of the present invention provides a method for replacing a sector for writing data onto a sector providing a recording area on a recording disc. Upon failure in the writing, the method performs a retry until a predetermined number of retries is reached, treats the sector as a defective sector upon failure in the last retry of the predetermined number of retries, and writes the data to another sector. The method comprises: a step of storing a retry count as retry count information for each of recovered sectors recovered from the failure through success in the writing of data during the retry; and a step of sector replacement control for selecting a replacement sector for the defective sector detected upon the failure in the writing onto the recording disc for which the retry count information is stored by the storing section. The replacement sector has a retry count stored as the retry count information smaller than that of the defective sector.
A fifth aspect of the present invention provides a recording disc for recording data written onto a sector providing are cording area. Upon failure in the writing, a retry is performed until a predetermined number of retries is reached. Upon failure in the last retry of the predetermined number of retries, the sector is treated as a defective sector, and the data is written onto another sector. A retry count is recorded as retry count information for each of recovered sectors recovered from the failure through success in the writing of data during the retry.
According to the present invention, when data is written onto a recording disc that includes restored sectors restored through retries after having failed to accept data at least one time, and if there is a failure in writing data onto a sector, a replacement sector is selected which will not require as many retries as needed for the restored sectors for the writing of the data.
In other words, the restored sectors, i.e. sectors which are made usable through the retry are given low priority for serving as a replacement sector because of a high risk of failure in data writing. Thus, it is possible to select a sector to which the data writing will be successful at the first attempt, without requiring any retries for example. Therefore, even if there is a failure in data writing onto a sector, there is a high probability of success in the replacement sector, and the number of retries and the time necessary for the retry procedures are held minimum, making possible to decrease the access time.
Other objects, characteristics, and advantages of the present invention will become clearer from the following description of embodiments to be presented with reference to the accompanying drawings.